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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Mark Rutland <mark.rutland@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 150/219] drivers/perf: arm_pmu: handle no
 platform_device
Thread-Topic: [PATCH AUTOSEL for 4.9 150/219] drivers/perf: arm_pmu: handle no
 platform_device
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Date:   Sat, 3 Mar 2018 22:29:23 +0000
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From: Mark Rutland <mark.rutland@arm.com>

[ Upstream commit 7654137071fa706e5c91f4f27bc2a5cd7e435a9b ]

In armpmu_dispatch_irq() we look at arm_pmu::plat_device to acquire
platdata, so that we can defer to platform-specific IRQ handling,
required on some 32-bit parts. With the advent of ACPI we won't always
have a platform_device, and so we must avoid trying to dereference
fields from it.

This patch fixes up armpmu_dispatch_irq() to avoid doing so, introducing
a new armpmu_get_platdata() helper.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/perf/arm_pmu.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index b37b57294566..af82edc7fa5c 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -322,10 +322,16 @@ validate_group(struct perf_event *event)
 	return 0;
 }
=20
+static struct arm_pmu_platdata *armpmu_get_platdata(struct arm_pmu *armpmu=
)
+{
+	struct platform_device *pdev =3D armpmu->plat_device;
+
+	return pdev ? dev_get_platdata(&pdev->dev) : NULL;
+}
+
 static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
 {
 	struct arm_pmu *armpmu;
-	struct platform_device *plat_device;
 	struct arm_pmu_platdata *plat;
 	int ret;
 	u64 start_clock, finish_clock;
@@ -337,8 +343,8 @@ static irqreturn_t armpmu_dispatch_irq(int irq, void *d=
ev)
 	 * dereference.
 	 */
 	armpmu =3D *(void **)dev;
-	plat_device =3D armpmu->plat_device;
-	plat =3D dev_get_platdata(&plat_device->dev);
+
+	plat =3D armpmu_get_platdata(armpmu);
=20
 	start_clock =3D sched_clock();
 	if (plat && plat->handle_irq)
--=20
2.14.1